1. Field of the invention
The present invention relates to a pipe coupling fitted with means for draining leakage from the coupling.
In fluid distribution circuits, successive lengths of pipe are connected together by couplings which generally comprise an annular ring which is screwed onto one of the pipes and which draws the other pipe, by means of a collar, into close and fluid-tight contact with the first pipe.
When the pipes convey a dangerous fluid, for example an inflammable liquid, any leakage of fluid from the coupling could have very serious consequences, and means is provided for draining away the leaking fluid to a place where it presents no danger.
2. Description of the prior art
In connection with a fuel feed circuit for the fuel injectors of a gas turbine engine, FR-A-2510714 discloses a drainage device composed of a sleeve enclosing the entire coupling, and fluid-tight seals between the sleeve and the two pipes, the sleeve having an outlet hole communicating with a drain pipe leading to a remote, safe area.
Thanks to this sleeve, any leakage of fuel from the coupling is confined within the sleeve and can only run out through the outlet hole and the drain pipe to the remote area.
However, this is a bulky and complex device, which adds to the weight of the coupling, and the installation of which demands extra time. Furthermore, the device needs to be removed and refitted each time the coupling has to be worked on for maintenance or repair. In extreme cases, it is also possible to forget to fit, or refit, the leakage drainage sleeve.
Also known is U.S. Pat. No. 4185462, which discloses an arrangement whereby the annular coupling ring itself constitutes the drainage sleeve, but in this case it is necessary to maintain the interior of the sleeve and the drain pipe at a lower pressure than the zone outside of and surrounding the coupling and its sleeve.
In addition, the angular orientation of the outlet depends on the tightening of the coupling ring, which poses difficulties, even impossibilities, for the connection of the drainage pipe.
Also known from GB-A-2 107 809 is a coupling in which one of the pipes is terminated by a female end member having a bore with two stepped sections, and the other pipe is terminated by a male end member with two stepped surfaces fitting into the two stepped bore sections of the female member with a sealing ring surrounding each of the two surfaces of the male member. In this manner, a leakage chamber is formed in the female member between the two sections of the bore, and the chamber is connected via an outlet hole to a drain pipe.
To the extent that the main seal between the male and female members is ensured solely by the sealing ring surrounding the end of the male member, such a device can only be applied to pipes conveying liquids at low pressures.
Here also, the angular orientation of the outlet cannot be chosen freely since it depends on the manner in which the pipe with the female member is installed.